This project is a controlled study of the effect of plasmapheresis on the clinical outcome of patients with the acute Guillain-Barre syndrome. It is a multi-institute study. Patients are randomized. Patients in one arm of the study receive conventional therapy; those in the other receive plasmapheresis. As the present time we have entered 105 patients into the study. Our total goal is 250 patients, one-half in the control group, one-half in the pheresis group. Review of the general data to date indicates that the randomization process is working satisfactorily, the data is being collected in a standardized and accurate way, and that there have not been significant medical problems associated with pheresis. Interim review of the first 105 cases indicates that there is yet no definitive answer as to whether plasmapheresis is beneficial in the early course of severly ill patients with the Guillain-Barre syndrome. On this basis it is proposed to continue this study through the full 250 patients as was originally proposed.